Computer generated aircraft displays have become highly sophisticated and are capable of displaying a substantial amount of flight management and control information, which gives flight crews more effective control of their aircraft and helps to reduce their workload. This reduction in flight crew workload results in fewer pilot errors and thus enhances flight safety. In this regard, electronic displays, such as Heads-Up Displays (HUDs) and Heads-Down Displays (HDDs), are used in aircraft as Primary Flight Displays (PFDs) to display important flight management and control information to flight crews.
Flight Path Vectors are known and widely used in HUDs and HDDs in PFDs. A Flight Path Vector (also known as a Flight Path Marker) is a symbol displayed on a PFD, which represents the sum of all of the forces acting on the aircraft involved, and indicates the direction or track of the aircraft's movement through space. The Flight Path Vector information displayed may be obtained from an onboard inertial guidance system, navigation system, Global Positioning System (GPS) receiver, attitude sensors, etc. In any event, Flight Path Vectors have proven to be an effective visual tool for controlling aircraft and reducing the workload for flight crews.
Flight Path Vectors are typically displayed as circular symbols. For illustrative purposes, a pictorial representation of a conventional electronic aircraft display, which illustrates a conventional use of a Flight Path Vector, is shown in FIG. 1. Referring to FIG. 1, display 100 can represent a PFD in an onboard electronic display (e.g., HDD). As shown, display 100 includes, among other things, a Flight Path Vector symbol 102 and an airport runway symbol 104. As the aircraft approaches an airport for landing, the pilot locates the intended target (runway 104, in this illustrative example) on display 100, and aims the aircraft in the direction of the target (runway 104). The pilot aims the aircraft at the target (runway 104) by controlling the aircraft's movement, so that the target remains in the close vicinity of the circular symbol representing Flight Path Vector 102. The optimum condition for landing is for the aircraft to be aimed directly at the nearest end of the runway. Consequently, the pilot attempts to control and aim the aircraft so that the Flight Path Vector symbol 102 is placed directly on the nearest end of the runway symbol 104. Alternatively, if a HUD is being used, the pilot may see an actual runway, so in this case, the pilot attempts to control and aim the aircraft so that the Flight Path Vector symbol (e.g., similar to symbol 102) electronically displayed on the HUD is placed in perspective directly on the nearest end of the actual runway being seen through the HUD screen.
Notwithstanding the distinct advantages of the use of Flight Path Vectors on aircraft displays, a significant drawback of existing aircraft displays is that the existing Flight Path Vector symbols (and other similar symbols being displayed) can obscure the targets that the pilots are attempting to see. For example, as illustrated by display 100 in FIG. 1, Flight Path Vector symbol 102 is shown covering and obscuring a significant portion of runway symbol 104. Since the size of Flight Path Vector 102 typically remains the same on display 100, and runway symbol 104 (or the actual runway being seen) is displayed or viewed in perspective (i.e., appears smaller at a longer distance), the Flight Path Vector symbol can significantly obscure the target especially at the longer distances. This loss of visual contact of the target by the pilot decreases the accuracy of the pilot's aim, and thus increases the possibility that navigation errors can occur. Therefore, it would be advantageous to have a system and method that enhances the visibility of a target on an electronic display when a Flight Path Vector symbol (or other symbol) is also being displayed. As described in detail below, the present invention provides such a system and method, which resolves the target visibility problems encountered by pilots with existing aircraft displays and other prior art displays, and thus facilitates target aiming and aircraft control by pilots using electronic displays.